Retrospective, population-based cohort study of colorectal cancer mortality following an organized FIT-based screening program

A retrospective, population-based cohort study in Basque Country (Spain, approximately 2.2 million inhabitants) evaluated the assocation between an organized FIT-based screening program and CRC-specific mortality. The biennial FIT-based CRC screening program targeting asymptomatic individuals aged 50 to 69 years was initiated in 2009. In this cohort study of 438 134 total all-cause death from 2004 to 2024, 16 298 (3.7%) were attributable to CRC. Age-standardized CRC mortality declined form 32.8 to 23.1 deaths per 100 000 population between 2004 and 2024 (reduction of 29.6%; p=0.002). In individuals aged 50 to 69 years, CRC mortality declined by 50.1%. Segmented regression identified a significant inflection point in the year 2012, 3 years after screening implementation. Counterfactual analyses estimated a 46.2 relative reduction in CRC mortality compared with projected trends without screening. Among individuals aged 70 years or older, CRC mortality declined by 19.6%, corresponding to a 45.4% relative reduction compared with projected rates. The authors conclude that organized FIT-based screening was associated with substantial and sustained reductions in CRC mortality.